Detecting 10KHz - 50KHz

We have a cat scarer in the garden which is triggered by a PIR. Whatever it is doing it is not scaring the local cats who still regularly visit us and leave their smelly presents in our flower beds

The scarer is being triggered, as can be seen from its LED indicator, but I am not sure if it is actually producing any output. It certainly has no effect on the cats. I am looking for a way to detect the output to determine whether it is outputting anything

According to the specification the output is in the range 10KHz-50KHz and is adjustable, but there is no indication of its actual frequency. Any suggestions as to how to detect whether the scarer is working will be gratefully received

You can hear if it works at 10 kHz. If so it most probably works for the other frequencies as well. What's the output device of the cat scarer?

Higher frequencies can be received by piezos, but without knowing the exact frequency response characteristic of the piezo you cannot be sure of the amplitude of the scarer output.

Place a cat and see what happens :nerd_face:.

Velleman do a simple heterodyne bat detector.

Not at my age. I may have to recruit a younger helper

I don't know as my wife won't let me take it to bits in case it needs to be returned !

One reason for keeping the cats away is to stop them stealing the food that we put out for hedgehogs. I have a security camera set up to record what happens overnight and have seen one particular cat meander across the patio and set off the scarer with no apparent effect on the cat at all

The instructions with the scarer say that we should experiment with its frequency setting in an attempt to discover a frequency that annoys the cats but also says that it may take some time for the cats to get fed up with the noise and keep away which sounds to me like a way of saying that if it does not work then don't blame the seller

Not to make too fine a point, but wouldn't it scare hedgehogs too?

Quite possibly, hence the camera to see what is going on. I was hoping to hit upon a combination of sensitivity, frequency and positioning of the scarer that would deter the cats and not the hedgehogs

The hedgehog or hogs (we can't tell them apart) are still visiting and the food dish is in an enclosed wooden box that the hogs can get into but not the cats, and the food is being eaten overnight so we are fulfilling one objective at least

As I said in my original post, hogs aside, we also have an ambition to deter the cats to stop them leaving smelly presents for us and the hog food on the patio makes a good test case

I'd assume the cats just aren't bothered. I think animals usually get used to sounds once they realize there's no danger. From what I've read, similar methods don't work on rats.

Now... If a dog comes running-out every time they hear that sound that's classical conditioning and they will quickly learn to stay away! :smiley:

I know someone who had good luck repelling deer with a motion activated sprinkler.

My 9yo found a water pistol deterred the local cats, they don't seem to like a shower.
When the foxes moved in to the garden this spring, the cat visits also got a lot less.

Could you adopt a fox?

The marketing from the company we bought the scarer from certainly sounds like bullshit, but it was bought on the recommendation of a neighbour who has 4 of them in her garden and since installing them "has not seen hide nor hair of a cat" and nor have they left here any smelly presents under the cover of darkness

I can't help feeing that we we will be returning the scarer under the 45 day "return if you are not happy" guarantee

Maybe the cat it doesn’t work on is old and can’t hear it as well?

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Maybe you could tap into one of the transducers on an ultrasonic range module.

ROTFLBTC :slight_smile:

I just realised - it's illegal to disturb bats in the UK, and I know that my local common pipistrelles operate around the 45kHz mark, and the soprano pipistrelles up to around 55kHz, so your cat-scarer may be illegal, if it's found it troubles your local bat population

My experiments with an HC-SR04 sensor came to nothing but an Android app has proven that there is increased ultrasonic activity when the scarer is triggered even though the 'phone cannot report the actual frequency due to limitations of its hardware

An illegal cat scarer. Who would have thought such a thing possible ? They would need to be very low flying bats to be disturbed, even assuming that the scarer is doing what it says, so I doubt that there is any danger of disturbing the local population of Natterer's Bats

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sample the output, divide the output by 2, 3, 4, 12 or whatever number you desire then send those divided frequencies to the speaker.

Sample the output how ?
I cannot get to the connections to the speaker output of the scarer

disconnecting the speaker, adding in an audio transformer that will give an output for the speaker and supply another secondary. Use the 2nd secondary to develop a signal for your processing.

Return it and get a water sprinkler and an electric valve. A little spray should dissuade them from entering the area.

Or another thought is to grind up some Irish Spring soap and leave it in small piles around the flower bed. I use my wife's old knee high stockings to hold the soap for easy replacement when needed.